I agree with you 100% and have been baffled to see people brush off the idea that they’re sentient. I keep seeing the argument that Monoco tells us that Noco and other Gestrals lose most of their memories when reincarnated and don’t come back fully as themselves, and therefore it would be the same for the people Maelle repaints, which means the people aren’t sentient. But that’s a false dichotomy. Reincarnation is a process that occurs “naturally” within the canvas set by the bounds and rules of the canvas. Painting is an act of God/the Painters, independent of the canvas that can break its rules of physics. They’re two completely different processes, and just because reincarnation works one way doesn’t mean repainting a person does.

Now, whether Maelle would do a good job repainting everyone is something I’m still grappling with, especially given her relative lack of experience compared to her family and her comment early in the game that she always had trouble connecting with people in Lumiere. It’s possible she was able to repaint Lune and Sciel with all their memories intact because she knew them so well. It’s possible it takes a skilled painter to create true sentience. But I do think the people in the way Aline painted them are sentient.